I need some help interpreting my data.

[Jaak]

I am trying to find an accurate loading for my S&W 686+ with a PC Lee 358-158-RF bullet. The 868's cylinder throats all measure .3580 give or take .0001 either way and the bore slugs out at 0.3570inch. Five of the seven throats measure .3580 exactly. I started with H110 and my Shooting Chrony shows velocities all over the place. Here's what I've gathered:

Grains	15.0	15.2	15.4	15.6	15.8
	1195	1284	1165	1193	1289
	1205	1297	1166	1245	1251
	1199	1269	1262	1229	1303
	1327	1293	1307	1340	1350
	1279	1164	1129	1141	1267
	1351	1347	1241	1236	1197
	1319	1218	1239	1175	1344
	1264	1305	1202	1267	1183
	1346	1202	1172	1196	1242
	1194	1191	1296	1246	1282
Average	1,267.9	1,257.0	1,217.9	1,226.8	1,270.8
Min	1,194.0	1,164.0	1,129.0	1,141.0	1,183.0
Max	1,351.0	1,347.0	1,307.0	1,340.0	1,350.0
Standard Deviation	65.6	59.4	60.3	55.1	55.3
Spread	157.0	183.0	178.0	199.0	167.0

I was expecting a somewhat linear slope trending upwards. Obviously something went wrong so I loaded up ten cartridges double checking everything. The bullets were weighed out to a max spread of 0.8 grains. The casings were all Winchester head stamp and trimmed to exactly 1.28 inches with two quality calipers used to double check length of every case. The powder was weighed out by a Frankford IntelliDropper and each load was double checked on a 505 balance scale. Each drop was 15.6gr, give or take three-hundredths of a Grain. (I was impressed with the FID's consistency)

I shot five rounds through the 686+

686+ 6"	Velocity
	1263
	1269
	1334
	1233
	1220
Standard Deviation	44.2
Min	1220
Max	1334
Spread	114
Average	1263.8

A spread of 114fps. What the hell is this? An SD of 44. Bullturds. At this point either I am doing something wrong with my loads, or my 686+ is a turd. I pull out my Contender to double check the last five rounds.

Contender 10"	Velocity
	1597
	1579
	1588
	1600
	1588
Standard Deviation	8.3
Min	1579
Max	1600
Spread	21
Average	1590.4

Holy Hanna! Now that's what I'm talkin' 'bout! A spread of 21 and an SD of 8! I'll take that any day! But the velocity scares me. Every manual that I have access to says this should be sprinting at 1100fps - 1400fps. I am absolutely sure I loaded 15.6 grains of H110. The 686+ was in the expected range, but the Contender was... not.

What is going on?

[sigep1764]

My thots go towards the crimp. It may be that the crimp on the lower velocity rounds may have been a little looser than the higher velocity rounds, thus not getting a complete burn as the higher velocity rounds. The longer barrel of the contender has more time to burn the powder. I could be wrong.

[sigep1764]

This also explains the faster velocities in the contender, longer burn time. Doesnt h110 and 2400 do their best work at higher loads?

[Bazoo]

Hmm, wonder if bullets are being pulled under recoil in the 686.

Higher velocity than expected in the contender will be due to barrel smoothness, lack of barrel/cylinder gap, perhaps tighter chamber, and different twist rate.

[Jaak]

My thots go towards the crimp. It may be that the crimp on the lower velocity rounds may have been a little looser than the higher velocity rounds, thus not getting a complete burn as the higher velocity rounds. The longer barrel of the contender has more time to burn the powder. I could be wrong.

This also explains the faster velocities in the contender, longer burn time. Doesnt h110 and 2400 do their best work at higher loads?

I applied a very heavy crimp, just as prescribed.

[sigep1764]

Also the contender has one chamber. The 686 has 6 or 7 depending on the model. Getting those to be as close to the same as possible will help the issue. Dougguy does that service here.

[Jaak]

Also the contender has one chamber. The 686 has 6 or 7 depending on the model. Getting those to be as close to the same as possible will help the issue. Dougguy does that service here.

I forgot to mention that I loaded and shot the revolver one cartridge at a time with all shots fired from the same position in the cylinder.

[dverna]

Have you calculated how much a 100 fps ES affects bullet drop at 50 yards? Not many folks can shoot well enough for it to matter.

How did the loads group? Chasing ES and SD might be important in wringing out a rifle load, but not so much with pistol loads at short range. If the load is shooting good groups, I would not worry about the statistics.

H110 is not a forgiving powder and others will chime in on that. I do not use it.

[littlejack]

I don't have any expieriance with the 357 cartridge and H110. However, I have loaded and shot hundreds in both my .41 magnum
revolvers. I can tell you for certain that H110 burns a lot more efficient with heavy powder charges. That is why the load data with H110 doesn't have a drastic drop in starting loads. So either stoke them hot, or switch to a faster powder, ie Alliant 2400, AA9 or there abouts. Are you using magnum primers? What size are the boolits you're using?

[Greg S]

Couple of quick thoughts, barrel cylinder gap, primer and mainspring tension.

SPMag primers are recommended for H110. If you are using them in all loads the only other difference between the two test beds is BC gap and firing pin striking force and protrusion. Check your strain screw and FP protrusion. Looking for .050 for protrusion. If this was a used specimen, was an action job performed prior?

If short protrusion, there are extended firing pins available. If it has a week hammer fall, a new strain screw or mainspring may be required.

[justindad]

What barrel lengths do you have for the Contender and for your revolver?
*
How far away is your chronograph?

[Tatume]

I ran a one-way analysis of variance on your original data. There is no significant difference between the means of any two velocities within the five loads.

Source: DF: SS: MS: Test Stat, F: Critical F: P-Value:
Treatment: 4 23522.68 5880.67 1.674461 2.578738 0.172539
Error: 45 158039.00 3511.977778
Total: 49 181561.68

[Forrest r]

It's good that you used 2 firearms to check the same load.

I'd be taking a hard look at the firing pin hits/lack of consistent hits.

[Tatume]

H110 is not a forgiving powder and others will chime in on that. I do not use it.

I agree, and add that my results with H110 and cast bullets are inferior compared to 2400. With jacketed bullets H110 can be very good, but the prevailing conjecture is that cast bullets do not resist movement enough for pressure to build to an optimal level.

[jdgabbard]

I agree, and add that my results with H110 and cast bullets are inferior compared to 2400. With jacketed bullets H110 can be very good, but the prevailing conjecture is that cast bullets do not resist movement enough for pressure to build to an optimal level.

LIGHT lead bullets I would agree with. If you start getting to heavies, where it has to work a little harder you build pressure a little better. But overall H110 is not my favorite. I prefer 2400, if I can ever get any more of it....

[Larry Gibson]

Jaak

As you discovered, H110 is not the best powder in a 357 revolver with cast bullets of 160 gr or less weight to use. Such bullets simply do not have the mass nor the friction coefficient for the H110 to ignite and burn as efficiently as other powders....in revolvers. The use of standard SP primers other than WSP primers or "magnum" SP primers will exacerbate the ignition of the H110 and efficiency of burn. So will shooting in colder weather. Additionally, in revolvers, the cylinder throats are essentially "free bores" which contribute to ignition and irregular burn. Then there is the barrel/cylinder gap which will vent pressure before peak psi is reached. All contribute to the "poor" ES/SDs you've gotten with the revolver. That is as it is. Best to switch to a better performing powder in revolvers with cast bullets such as 2400 or Blue Dot for magnum level loads.

As to the H110s performance in the closed breach Contender, nothing "hot" or out of the ordinary there. The velocities and their ES/SD is exactly as it should be. The Contender's closed breach barrel has none of the inherent revolver features mentioned to cause the ignition/burn problems that occur in revolvers. Also the closed breach Contender 10" barrel w/o the free bore and barrel cylinder gap is going to produce the higher velocity as you found. Your load in the Contender is pretty much the same as I have found in 3 separate Contender barrels and is consistent with Contender data in manuals.

[TurnipEaterDown]

I find W296/H110 to work fine in 44 Mag & 475 Linebaugh w/ cast (PB & GC) as long as it is loaded full charge. Very good groups - 50 yd 1-2 in 5 shot revolver groups w/ numerous bullets, good gun and well worn. (260-320 gr in 44, 400 gr in 475)

From a quick reference in a Lyman manual 357 data, both the revolver and TC data shown above are all that I think should be expected from a 357 in the guns shown - not a low pressure range of use being discussed for 296/110 in other words.

I would say that small sample statistics can be pretty misleading, and that the comment from Don (re: use - group expectation from revolver loads) is a good comment. Maybe the load shown groups very poorly in the poster's revolver, but if it groups good, I think I would disregard the statistics and just use it. Shoot it at 50 & 100 (if you want) and see what it does. Many loads I have that shoot good groups at useful range don't really have good looking small sample statistics, but they meet their goal.

Primer swaps will also sometimes tighten velocity and group spreads, and this can be evident more so with hard to ignite powders.

Also, an ambient temperature drop from 40 to just 20 °F can produce additional variability in revolver load velocity uniformity if the load is boarderline.

(edited to note weight in loads mentioned that shoot "well" in my experience, and my experience of ambient change effect)

[gwpercle]

With the 357 magnum I have had better accuracy results with 2400 and just lately some very promising groups with Accurate #7 ... Needs more work ...
I'm looking to try some Accurate #9 in heavy 357 magnum loads in place of 2400 ... as it might be the better for that application ... but only the target will tell .

I still haven't found any powders better than Bullseye , Unique and 2400, but some days they just aren't available ...so you gotta load whatever powders you can get !

Good luck with the H110 ... I don't have any advice for this one , used it very little and it didn't work for me .
Try different , hotter primers ... sometimes primers make a big difference in a load .
Gary

[TNsailorman]

My experience with H110 in a .41 magnum was that the loads above starting loads were by far the best in terms of accuracy. That is one reason I do not load H110 in the .41 magnum anymore, I do not like to run chamber pressures at the very limit of safety. And there was that warning in my manuals to "NOT" load H110 below the starting listed load. And there was a very narrow range between the starting load and the maximum load. That was enough for me. I quit using H110 in the .41. I gave away a 1/2 bottle of H110 and sure could use it now as it is about the only listed powder I can find for the 410 shotshell. james

[Jaak]

Couple of quick thoughts, barrel cylinder gap, primer and mainspring tension.

SPMag primers are recommended for H110. If you are using them in all loads the only other difference between the two test beds is BC gap and firing pin striking force and protrusion. Check your strain screw and FP protrusion. Looking for .050 for protrusion. If this was a used specimen, was an action job performed prior?

If short protrusion, there are extended firing pins available. If it has a week hammer fall, a new strain screw or mainspring may be required.

I've never used H110 before so I'm following the manuals exactly. Even to the point of using the same brand of primer recommendations. In this case it was Winchester SPP Magnum.